When you think of natural sources of energy, you might think of solar or wind power. When a few scientists at the Bristol Robotics Laboratory in England thought of natural sources of energy, they thought of a more personal source. They thought of urine.

The scientists at the robotics lab, a joint venture between the University of West England and the University of Bristol, have made phone calls, sent text messages and surfed the web on a Samsung cellphone that was powered for a 24-hour period by a bladder full of pee, or more technically, 500 milliliters of urine.

But don't start sticking your cellphone charger into the toilet. The urine was used to power microbial fuel cells, Ioannis Ieropoulos, a senior research fellow at the University of the West of England and leader of the project, explained to ABC News.

WHAT TO KNOW

Urine powered a cellphone for 24 hours

Researchers hope to bring the tech to the developing world as an alternative power source

A microbial fuel cell is an energy converter that converts one form of energy into another. Inside the devices are live cells or microbes -- the same you would find in a lake or in soil -- and they break down substance as their fuel and produce electricity as a by-product.

"We have been using urine as their feed stock," Ieropoulos explained. "We have a system that allows the feeding of urine into these microbial fuel cells, and the output we get is electricity. Just imagine the microbial fuels as analogous to batteries. We collected them, gave them urine as the fuel, and that's what is used to charge the mobile phone battery."

The findings of the study will be published this week in the Royal Society of Chemistry Journal, but this isn't just something for the science journals and books. The project is in part funded by the Bill and Melinda Gates Foundation, with the goal that the research and technology can have real-world applications, especially in the developing world.

The work happening in Ieropoulos' lab might one day help create what he calls smart toilets. "We have been thinking about smart toilets, which can be producing electricity while the waste is going down the drain," Ieropoulos said.

In less developed parts of the world, the goal is to create a system that could work without toilets. "What we have been asked to do is produce a technology that can go into the remote community location, be installed at the pit latrine -- in the hole in the ground -- and utilize some of that waste for electricity production."

While the team in Bristol is in the early stages of developing a phone that can be powered by urine, and right now the liquid has to be run through a complex series of tubes and cords, Ieropoulos believes that one day this type of technology could power a phone in times of distress.

"If one was at a remote location and they had this technology available, they could urinate into this technology and get the central electricity to charge up their phone and contact the people they had to contact if they were in a distressed situation," he said.

Though it might be tempting to make a "we hope they wash their hands" joke, Ieropoulos just wants people to know there are far greater implications to a phone powered by pee.

"The reality is that this technology allows us to turn something that was going completely to waste into something as useful as electricity."